1. Field of the Invention
The present invention relates to swing or rotary bolt locks in which part of the locking bolt pivots into and out of the lock housing.
2. General Background and State of the Art
Doors of safes, vaults, strong rooms, container and similar security closures (collectively called xe2x80x9csafesxe2x80x9d in this application) usually have at least one and preferably several safe bolts that reciprocate from a non-locking position to an extended locking position. In the locking position, the safe bolts extend from the safe door into receptacles in the adjacent safe walls. When the safe has more than one bolt, bolt works connect the bolts. The bolt works include linkages that move the safe bolts simultaneously when a user turns a single handle. A locking device cooperates with the bolt works to secure the safe bolts in their extended locking position.
So-called swing bolt or rotary bolt locking devices mount a bolt for pivoting between locked and unlocked positions. This application refers to the swing bolt within the locking device as the xe2x80x9cbolt,xe2x80x9d xe2x80x9cswing boltxe2x80x9d or xe2x80x9clocking bolt.xe2x80x9d The bolts that secure the safe door to the rest of the safe are called xe2x80x9csafe bolts.xe2x80x9d In the locked position, part of the locking bolt projects out of the housing. Through the swing bolt""s intersection with the mechanical bolt works when the swing bolt is in its locked position, the bolt works cannot move the safe bolts to their unlocked position. When the user enters the correct combination, the lock mechanism allows the locking bolt to pivot so that it is within the housing.
A handle on the outside of the safe connects to the bolt works. Pivoting the handle initiates movement of the bolt works. If the user enters the correct combination so that the locking bolt is not locked, the bolt works can pivot the swing bolt so that the swing bolt does not project from the housing. This is the unlocked position, which permits the bolt works to continue moving the safe bolts to their unlocked condition. That allows one to open the safe. If, however, the swing bolt is locked, the swing bolt blocks movement of the bolt works. That prevents the bolt works from withdrawing the safe bolts. Uyeda, U.S. Pat. Nos. 5,134,870 (1992) and 5,142,890 (1992), describe safes using swing bolt locks.
The locking mechanism within the lock housing blocks the bolt from pivoting to the unlocked position. The two Uyeda patents and other prior art locks have a solenoid within the housing. In the Uyeda patent, the solenoid plunger directly engages the locking bolt. The solenoid plunger of other prior art locks engages a locking plate that projects against the bolt. When the plunger or plate engages the bolt, the bolt normally cannot rotate to an unlocked position.
An electronic combination entry system controls the solenoid. Typically, the user enters the combination through a digital input pad. Butterwerk, U.S. Pat. No. 5,887,467 (1999), xe2x80x9cPawl and Solenoid Locking Mechanism,xe2x80x9d is an example of a lock that uses a key pad on a rotary handle. Rotary input through a dial also can generate an output. Internal circuitry senses entry of the correct combination and sends an electric signal to the solenoid. The signal causes the solenoid to withdraw the plunger, which, in turn, allows the locking plate to disengage the locking bolt. The handle then can manipulate the bolt works. Part of the bolt works pushes on the locking bolt to rotate the bolt about a shaft to its unlocked position. The bolt works then withdraw the safe bolts.
The prior art recognizes that applying sufficient force on a still-locked handle of a safe with a swing bolt lock through pounding, jostling or other manipulation can sometimes open the safe. The solenoid must be relatively small to fit within the lock housing. Therefore, the plunger also is small and weak. Further, having a smaller solenoid consumes less electric power. Since most such locks are battery-powered, decreasing electric consumption adds to battery life. Unfortunately, sufficient force from the handle through the bolt works against the swing bolt sometimes can apply enough force against the locking plate to break the plunger. Once the plunger breaks, the plate moves freely, which allows the swing bolt to pivot open. The bolt works are free to withdraw the safe bolts from their receptacle to open the safe.
The Uyeda patents and other prior art locks propose a solution to this problem. When one tries to rotate the handle without first entering the correct combination, the bolt pushes against the solenoid housing or the locking plate. The Uyeda patents have a notch in the periphery of the rotary bolt. The bore of the swing bolt, which rotates about a shaft or axle, is elongated. The elongated opening can move along the bore when one applies a force form the handle through the bolt works on the swing bolt. Thus, the swing bolt can move laterally. Lateral movement causes the notch on the periphery of the swing bolt to engage a safety key within the lock housing. That prevents further force from the swing bolt against the solenoid plunger or locking plate. The Uyeda patents also have a leaf spring that biases the swing bolt and its bore to a normal position relative to the shaft within the bore.
The mechanism in the Uyeda patents is complex and costly to build and assemble. Other prior art has simplified the mechanism, but the structure to bias the swing bolt relative to its shaft or axle has remained complex. For example, one swing bolt has a bolt plate mounted in a groove in the swing bolt. That plate has an opening over part of the elongated opening in the swing bolt. A spring within the bolt biases the opening in the plate to one end of the elongated opening. When force is applied to the bolt to cause it to pivot about the solenoid locking plate, the bolt plate slides on the bolt against the spring until the opening in the bolt plate is at the other end of the elongated opening in the swing bolt. That shifts the swing bolt sufficiently to case the notch of the periphery of the swing bolt to engage the key in the lock housing. The construction of the swing bolt with its sliding plate and internal spring is complex. Assembly costs are high and time consuming.
An object of the present invention is to disclose a pivoting or swing bolt lock that prevents the bolt from pivoting except when the user enters the correct combination. Specifically, an object of the present invention is to disclose a lock that prevents a thief or other unauthorized user from supplying sufficient force to the outside handle to break internal parts of the lock to gain access to a safe. Providing that object with few parts that can be assembled easily and efficiently is another object of this invention.
The present invention includes a housing having a bolt opening into and out of which a rotating or swing locking bolt pivots. The swing bolt has an elongated opening for receiving the shaft.
A solenoid mounts within the housing. A plunger on the solenoid engages a locking plate. When the lock is in its locked condition, the locking plate engages the locking bolt to prevent the swing bolt from pivoting. When a user enters the correct combination, the plunger disengages the locking plate so that the latter is free to slide out of its engagement with the locking bolt. A handle connected by a shaft through the outside of the safe drives bolt works. Movement of bolt works acts on the swing bolt and pivots it to the unlocked position. Because the locking plate is out of the way, it does not prevent the swing bolt from pivoting.
If an unauthorized user applies sufficient force to the handle through the bolt works against the swing bolt, the intersection of the swing bolt and the locking plate becomes an axis of rotation. The swing bolt rotates slightly on that axis because the opening in the swing bolt through which the shaft extends is elongated. This permits some lateral movement of the swing bolt relative to the shaft. As a result, a notch on the swing bolt periphery engages a safety key or other part of the housing, a part that the swing bolt would miss if the bolt were rotated properly with the locking plate out of the way.
The shaft has a generally flattened surface, and one end of the shaft-receiving opening that faces the flattened face of the shaft also is generally flat. By xe2x80x9cflat,xe2x80x9d applicant means that generally cylindrical surfaces are flattened. They need not be actually flat. Further, though the exemplary embodiment shows the entire height of the opening and the shaft being flattened, one could flatten parts of the surfaces.
The shaft has a bore on the flattened surface that receives a compression spring. The spring extends from the shaft to the flattened surface of the opening. The spring retains the locking bolt in its normal position on the shaft unless forces caused when one tries to open the lock forcibly overcomes the spring force.